Back-pressure or noncondensing steam turbine



Nov. 1, 1927. Y 1,647,421

0. A. WIBERG BACK-PRESSURE 0R NONCONDENSING STEAM TURBINE filed July 16. 1926 2 Sheets-Sheet 1 Nov. 1, 1927. 1,647,421

o. A. WIBERG BACK PRESSURE OR NONCONDENSING STEAM TURBINE Filed July 16. 1926 I 2 Sheets-Sheet? Patented Nov. .1, 1927.

' OSCAR ANTON Wrasse, on i rzrsronasiv'nnnn. I

BACK-PRESSURE R NONCONEEZNSING STEAM TURBINE.

Application filed J'u1y-16,-192 6, Serial No. 122,834, and in swede August 15, 1925,

This invention relates to the back-pressure or non-condensing type of steam turbines and more particularly toturbmes of said type having blade Wheel-s rotating: in opposite directions.

sure above condenser pressure exists in the steam outlet and, consequently, also a higher temperature. '10 The object of this inventionis to prevent heat from being transmitted from the outlet of the turbine to the turbine bearings and to the electrical generators, or other machines coupled to the turbine, to an extent that would cause damage to such machines.

To this end, the steam chests of the turbine are connected to or formed integral with an inner turbine casing, preferably provided with ventilation means, said inner casing being in turn surrounded by an outer turbine casing through which circulation of air may take place.

In the drawing Flg. 1 is a vertical longi-' tudinal section of a turbine embodying the invention and,

Fig. 2 is a side elevation, partly in cross section, of the turbine. g The blade system 1 of the turbine and the associated parts are mounted in a casing comprising two vertically arranged plates each having an inner or central fiat portion 2, on which said system is mounted, and an outer dished shaped portion 3 surrounding the central portion. These outer portions 3 are formed with peripheral flanges 4 connected together by bolts 'or rivets 5. Said plates have a spiral periphery as shown in Fig. 2 so that the dished portions 3 form a substantially annular chamber 6 surrounding the blade system and a conduit? for the exhaust steam. That part of the casing forming the chamber 6 has an insulating covering H 8, and if desired the latter may cover the discharge conduit. The whole inner casing is enclosed in a casing 9 hereinafter referred to as the outer casing, said outer casing being spaced from the inner casing so as to form a free space 10 around the inner casing.

' Openings 11 are formed in the outer casing to permit circulation of air in said space and permit the outer casing 9 to be maintained at a temperature sufliciently low to prevent expansions and stresses thatmay act detrimentally.

I The steam chests 12 and the steam admission passages 18, which communicate with turbines that work condensingthe outer cas- As' compared with the usual type of turbine, work-ing condensing, a presthe blade system 1/are,connected to or, 'as' shownin Fig. 1, formedintegral with the inner-turbine casing. .As in the casing of ing 9 supports ,the bearings 14,14.- and forms .a bed frame15. i The'inner casing surrounding the blade system receives the exhaust steam'and is so constructed and arranged as to prevent those expansions to which it. is subjected, due to 7 the high temperature of the exhaust steam, from having any disadvantageous effect on adjacent parts. To this end, the walls of the chamber 6. are formed resilient inasmuch as their thickness is so chosen as to keep the value of the axial thrust, due to heat eX-. pansion, withinmoderate limits. In orderto prevent the formation of rust on the inner turbinecasing said casing is provided with ventilation valves or cocks 16 which are held open when the turbine is at rest to permit the circulation of air through the interior of the turbine whereby the system will be kept dry. These valves may be of any type desired, provided they are ofsufiicient size to permit proper ventilation. In actual use an opening is provided in the turbine casing controlled by a screw cover.

What I claim is:

1. In a non-condensing steam turbine of the type having blade wheels rotating in op- .posite directions, the combination of steam chests, an inner casing surrounding the blade wheels, and connected to the walls of said steam chests, ventilation means on said casing, and an outer casing surrounding said first mentioned casing so as to leave a free space therearound, said outer casinghaving holes formed in it to permit circulations of air in said space.

2. In a non-condensing steamturbine of the type having blade wheels rotating in opposite directions, the combination of steam chests, separate members of resilient material connected to thewalls of said steam chests and to each other so as to form an inner turbine-casing, ventilation means on said casing, and an independent outer turbine. casing surrounding said first mentioned casing so as to form a free space therearound, said outer casing havingholes formed in it to permit circulation of air in said free space.

positedirections, the combination of steam blade Wheels and connected to the Walls of said steam chests, ventilation means on'said casing, an insulating covering on the Outside of said casing, and an independent outer casing supporting bearings for the turbine and forming the bed-frame thereof, said outer casing surrounding said first-mentioned casing so as to form a free space therearound and having holes formed in it to permit circulation of air in said space.

4. In a non-condensing steam turbine of the type having blade Wheels rotating in 0pposite directions, the combination of steam 15 chests, an inner casing surrounding the blade Wheels and forming the exhaust chamber of the turbine, said inner casing being connected to the Walls of said steam chests,

ventilation means on said inner casing, an

insulating covering on the outside of said casing, and an lndependent outer'turbme casing supporting bearings for the turbine and forming the bed-frame thereof, said' name.

OSCAR ANTON VVIBERG. 

